Two cases of congenital aneurysm of sinus of Valsalva, ruptured into the right ventricle, and associated with ventricular septal defects, were undergone intracardiac repair with the aid of extracorporeal circulation using Bentley bubble oxygenator and moderate hypothermia. Case 1. A 20 year old male, with the chief complaints of palpitation and dyspnea, was admitted to Kyungpook National University Hospital on Dec. 16, 1976. Continuous machinery murmur was heard best at left 3rd. intercostal space along the sternal border. Retrograde aortography disclosed aneurysm of the right coronary cusp, which ruptured into the right ventricle. Utilizing cardiac bypass and moderate hypothermia, the right ventricle was opened and aneurysm was closed by direct sutures. Associated ventricuar septal defect was directly ,closed and suture line was reinforced by Dacron patch. Total bypass time was 112 minutes and total aortic cross clamping time was 37 minutes. Assist ventilation was carried out for 28 hours postoperatively. His postoperative course was smooth except removal o1 substernal hematoma and he was .discharged on 24th postoperative day. Case 2. A 28 year old man was admitted to our Hospital on June 9, 1976. two weeks prior to this admission, suddenly he had collapsed while he was walking on the street. Following `this episode, palpitation, dyspnea on exertion and frequent respiratory infection developed. Grade IV systolic murmur was heard best at 3rd intercostal space along the sternal border. Retrograde aortography confirmed the diagnosis of rupture of aneurysm of the sinus Valsalva ruptured into the right ventricle. Under the cardiopulmonary bypass the right ventricle was opened and ruptured aneurysm and infracristal ventricular septal defect were directly closed and reinforced with Dacron patch. Postoperative course was uneventful and he was discharged on 14th postoperative day. The pathogenesis of aneurysm of the sinus Valsalva and mode of diagnosis were discussed. Principle of surgical repair was presented.[KTCS 1977;1:133-139]